The average spectrum of a disordered f.c.c. vicinal surface is obtained from effective medium Green's function. The disorder is restricted to the surface plane and the scattering in the surface is treated in the Coherent Potential Approximation. The method applies to site-diagonal disorder and is valid for any crystallographic orientation. An application is made for an s-like Tight-Binding Hamiltonian with substitutional disorder. Depending on the strength of the perturbation potential, resonances or local bands are found in the surface spectrum.The average spectrum of a disordered f.c.c. vicinal surface is obtained from effective medium Green's function. The disorder is restricted to the surface plane and the scattering in the surface is treated in the Coherent Potential Approximation. The method applies to site-diagonal disorder and is valid for any crystallographic orientation. An application is made for an s-like Tight-Binding Hamiltonian with substitutional disorder. Depending on the strength of the perturbation potential, resonances or local bands are found in the surface spectrum.